The invention pertains to a brake assembly, and more particularly to a parking brake assembly for a skid steer loader vehicle. Skid steer loaders are propelled and maneuvered by driving the wheels on one side of the vehicle at a different speed and/or in an opposite direction from those on the other side so as to achieve a turning motion. The "steering" is controlled by the operator using a pair of levers, one on each side of the operator's feet, which may be moved independently in a fore and aft direction to cause the wheels on that side of the machine to rotate at a speed and at a direction corresponding to the position of the lever. For example, both levers may be moved forward in either a forward or rearward manner causing the loader to move straight forward or back up at variable speeds depending on the position of the levers. Or, the driver may move the levers simultaneously but to a greater degree on one side than the other thus causing the loader to execute a turn. Or, by pushing one lever in one direction and pulling the other in the opposite direction the loader is turned on its axis or spun around virtually in its own tracks.
Hydraulic drive means include independent transmissions for each set of wheels on opposite sides of the vehicle. The levers provided in the operator's compartment control the inputs to each transmission independently. The transmissions comprise independent hydraulic motors carried on a transmission case, each having an output shaft extending into the case carrying drive sprockets thereon which by means of independent chain drives are connected to respective wheel sprockets for each set of wheels. Thus the output shafts of the hydraulic motors control input to the wheels and consequently speed and direction of the vehicle. Stopping of the vehicle is normally achieved by placing the control levers in a neutral position to stop fluid flow to the hydraulic motors. With the control levers in the neutral position, fluid flow from the hydrostatic pumps driving the hydraulic motors associated with the transmission is halted thus effectively stopping the hydraulic motors and rotation of the output shaft.
Little effort has been made previously to provide positive braking means for skid steer vehicles. Typically, a skid steer vehicle is stopped by returning both control levers to a neutral position. However, such braking means makes no provision for the inadvertent movement of one or more of the control levers which could cause the vehicle to operate accidentally and out of the control of the operator. Further, in a hydrostatic drive means such as typically used in a skid steer vehicle, it is difficult to achieve a null output position and a skid steer vehicle left unattended with the engine running and the control levers in the neutral position tends to "creep" or inch forward. Accordingly, it would be desirable to provide positive braking means for such skid steer vehicle whereby the drive means of the vehicle could be positively locked against relative motion.